We would apply the formula for determining simple interest which is expressed as
I = PRT/100
Where
I represents the interest
P represents the principal or amount borrowed
T represents time in years
R represents the interest rate
From the information given,
P = 10500
R = 13.5%
T = 4.5 years
Therefore,
I = 10500 * 13.5 * 4.5/100
I = 6378.75
The total amount owed would be the sum of the interest and the initial amount borrowed
Total amount owed = 10500 + 6378.75 = $16878.75
